Can not set discount base on cart line item index instead of the product Variant

[BaoMai_LA]

For now Shopify only have 2 options for discount

• orderSubtotal (OrderSubtotalTarget)

  The subtotal of the target order.

• productVariant (ProductVariantTarget)

  The target product variant.

https://shopify.dev/docs/api/functions/reference/order-discounts/graphql/common-objects/target

Do we have any way to set discount on cart item index, instead of the productVairant 

In my case, there are 2 items in cart with the same variant. But they have different properties for Private Sale

Input:

{
  "cart": {
    "lines": [
      {
        "id": "gid://shopify/CartLine/0",
        "quantity": 2,
        "cost": {
          "amountPerQuantity": {
            "amount": "785.95"
          }
        },
        "merchandise": {
          "__typename": "ProductVariant",
          "id": "gid://shopify/ProductVariant/47641613599039",
          "product": {
            "id": "gid://shopify/Product/9118075814207"
          }
        }
      },
      {
        "id": "gid://shopify/CartLine/1",
        "quantity": 1,
        "cost": {
          "amountPerQuantity": {
            "amount": "785.95"
          }
        },
        "TeamStore_Private": {
          "value": "$765.95"
        },
        "merchandise": {
          "__typename": "ProductVariant",
          "id": "gid://shopify/ProductVariant/47641613599039",
          "product": {
            "id": "gid://shopify/Product/9118075814207"
          }
        }
      }
    ],
    "buyerIdentity": null
  }
}

Output:

{
  "discounts": [
    {
      "targets": [
        {
          "productVariant": {
            "id": "gid://shopify/ProductVariant/47641613599039",
            "quantity": 1
          }
        }
      ],
      "value": {
        "fixedAmount": {
          "amount": 20
        }
      },
      "message": "Team Store"
    }
  ],
  "discountApplicationStrategy": "ALL"
}

The discount should be affect for the first item has Private Sale instead the second one.

[tobebuilds]

You can't target a specific line item with Functions discounts right now.

There's a popular GitHub discussion thread where devs are requesting this functionality: https://github.com/Shopify/function-examples/discussions/199